Effects Of Lysolecithin On Production Performance,Plasma Biochemical Indexes And Nutrient Digestibility Of Fast-growing Brown Feather Broilers In Different Diet Energy Level

The objective of this study aimed to evaluate the effects of supplemental lysolecithin to two energy level feeds on growth performance,slaughter performance,meat quality,digestive enzyme activity and nutrient digestibility of Fast-growing Brown Feather Broilers fed with diets containing normal and low energy.Providing a scientific basis for the application of lysolecithinto increase the energy utilization in Fast-growing Brown Feather Broilers.In the experiment,a total of 1,080 one-day-old healthy brown-feather broiler chicks with the same average initial body weight,were randomly divided into 6 groups,with 6replicates in each group,and 30 chicks in each replicate.The experimental groups were assigned as follows: 1)Control group,fed with basal diet;2)Control group +lysolecithin500,basal diet supplemented with 500 mg/kg lysolecithin;3)Low-energy group,60 kcal/kg of metabolizable energy reduced from the basal diet;4)Low energy group +lysolecithin 500,500 mg/kg lysolecithin was added to the low-energy diet;5)Low-energy group + llysolecithin750,energy-reducing diet adding 750 mg/kglysolecithin;6)Low-energy group +lysolecithin 1000,1000 mg/kg lysolecithin was added to the energy-reducing diet.The feeding period last for 52 days including two feeding phases: the starter phase(1-21days)and grower phase(22-52 days).All broilers were free access to diets and drinking with24-hour lighting.Immunization and daily management were performed according to the conventional cage management.At the age of 21 days and 52 days,one chicken was randomly selected from each replicate,and then slaughtered and sampled after the blood was drawn.The results are shown as below:(1)Compared with the control group,reduction of the energy had no significant effect on the average daily gain of the Fast-growing Brown Feather Broilers during the whole period(P>0.05),but increased the feed conversion rate(FCR);On-top application oflysolecithin at a dosage of 500 mg/kg feed reduced FCR by 0.06 pointswhile increased the average daily gain by 2.8%;Broilers fed with low-energy diets containinglysolecithin displayed comparable growth performance to that in control group giving basal diets.(2)Compared with the control group,adding lysolecithin to the basal diet and reduction of dietary energy as well as supplemental lysolecithin had no significant effects on the total evisceration weight,slaughter rate,leg muscle rate,abdominal fat rate(P>0.05).(3)Compared with the control group,the addition of 500 mg/kglysolecithin to the basal diet significantly increased the redness a* value of broiler thigh muscle(P<0.05)(4)Compared with the control group,the addition of 500 mg/kglysolecithin to the basal diet had no significant effect on the contents of serum TC,TG,HDL and LDL of broilers in(P>0.05);However,the serum TG content of broilers in the low-energy group was significantly reduced in the starter phase(P<0.05).Compared with the low-energy group,adding 750 mg/kg lysolecithin to the energy-reducing diet significantly increased the serum TG content(P<0.05).(5)In the starter phase(1-21d),compared with the control group,the addition of 500mg/kglysolecithin to the basal diet significantly increased the height of ileal villi in the starter phase;while the depth of jejunal crypts in the reduced energy group was increased,and the height of ileum villi was significantly higher than that of the control group(P<0.05).Compared with low-energy diet,the addition of lysolecithin to energy-reducing diets significantly reduced the depth of jejunal crypts and ileum crypts,and increased the ratio of jejunal villi/crypt and ileum villi/crypt(P<0.05).In the grower phase(22-52d),compared with the control group,the addition of 500 mg/kg lysolecithin to the basal diet significantly increased the ileal villus height and the villus/crypt ratio(P<0.05);Reduction of dietary energy significantly increased the height of jejunum villi and the villus/crypt ratio(P<0.05),decreased the depth of crypts,and increased the villus/crypt ratio of the ileum(P<0.05).Compared with low-energy diets,the addition of lysolecithin to low-energy diets significantly increased the height of jejunum villi and villi/crypt ratio and reduced the depth of crypts(P<0.05);while low-energy diets added 750 mg/kg and 1000 mg/kg lysolecithin also significantly increased the ileal villi height and the villus/crypt ratio(P<0.05),and reduced the crypt depth(P<0.05).(6)Compared with the control group,the addition of 500 mg/kg lysolecithin to the basal diet significantly increased the total intestinal apparent digestibility of dry matter and crude protein(P<0.05)in the starter phase(1-21d)of broilers,and significantly improved the total intestinal apparent digestibility of crude fat in the grower phase(22-52d)(P<0.05).Compared with the control group,the dry matter,crude protein,and energy digestibility of the energy-reduction group increased significantly(P<0.05)in the starter phase,and the dry matter,crude fat,crude protein,and energy digestibility were significantly improved(P<0.05).Compared with the energy-reducing group,the effect of adding lysolecithin to the energy-reducing diet on the digestibility of various nutrients was not significant(P<0.05).(7)Compared with the control group,the lysolecithinsignificantly increased the duodenal lipase activity of broilers in the starter phase(1-21d)(P<0.05);lowering the energy level also significantly increased the broiler lipase activity(P<0.05)but It was lower than the lysolecithin group(P<0.05).Compared with the energy-reducing group,adding 750 mg/kg lysolecithin to the energy-reducing diet significantly improved the jejunal amylase activity and chymotrypsin activity of broilers in the starter phase(1-21d)(P<0.05).(8)The addition of 500 mg/kg lysolecithin to the basal diet significantly improved the basal diet except for Val(valine),Met(methionine),Phe(phenylalanine),and Leu(leucine).(P<0.05).The reduction of energy levels significantly increased the apparent ileal digestibility of dietary Gly(glycine),Arg(arginine),Tyr(tyrosine)and Lys(lysine)(P<0.05).The addition of 750 mg/kg lysolecithin to the energy-reducing diet significantly improved The apparent ileal digestibility of 11 amino acids except for Arg(arginine),Tyr(tyrosine),Met(methionine),Phe(phenylalanine)and(P<0.05).In conclusion,supplementing lysolecithin to normal and low energy diets can reduce the feed to gain ratio,improve the redness of leg muscle,increase the level of serum fat metabolites,improve the intestinal morphology,nutrient digestibility and promote the function of liver lipid metabolism.